1. Field of the Invention
The present invention relates to an ophthalmologic apparatus having an alignment function for automatically starting the measurement of an intraocular pressure or a photographing operation with respect to an eye to be examined.
2. Description of Related Art
An ophthalmologic apparatus having a so-called automatic alignment function is conventionally known. In the ophthalmologic apparatus, alignment target light is projected onto an eye to be examined of an examinee, and light reflected by a cornea of the eye is guided to a position detecting sensor by an optical system for receiving reflected light. A measuring unit is automatically aligned with the eye on the basis of an output of the position detecting sensor.
In such an ophthalmologic apparatus, an examiner makes a rough alignment between a measurement optical axis of the measuring unit and the cornea of the eye by operating a joy stick, etc. while the examiner observes through a finder or a monitor. After the rough alignment is completed, a measurement optical axis of the measuring unit is automatically aligned with a vertex of the cornea of the eye on the basis of the output of the position detecting sensor. Thereafter, when a shifting quantity between the measurement optical axis of the measuring unit and the cornea vertex of the eye is equal to or smaller than a predetermined value by the automatic alignment, the measurement of the intraocular pressure, etc. or the photographing operation with respect to the eye is automatically started.
However, when the eye is a diseased eye such as a cataract, there is a case in which disturbance light except for the reflected light from cornea is entered to the position detecting sensor. In this case, there was a case in which no automatic alignment with the cornea vertex of the eye can be suitably made and the automatic measurement is started in a position shifted from the cornea vertex of the eye. Therefore, no exact measurement value could be obtained and the obtained measurement value was not reliable. Further, it was required to make the measurement again, which increases a burden to the examinee.